1. Field of the Invention
This invention relates to an improvement in a motor driven sewing machine comprising an electrical signal generator for generating an electrical signal in response to a predetermined rotational angular position of the main-shaft of the sewing machine.
2. Description of the Prior Art
A motor driven sewing machine was recently developed which is provided with an electrical signal generator for generating an electrical signal in response to a predetermined rotational angular position of the main-shaft of the sewing machine in order to control the needle position and the cloth feed in response to the electrical signal. Examples of such a sewing machine are disclosed in the U.S. Patent Application Ser. No. 364,835 entitled "Sewing Machine Equipped with Pulse Generator", filed May 29, 1973 by John W. Wurst and James E. O'Brien and issued June 11, 1974 as the U.S. Pat. No. 3,815,531 and assigned to The Singer Company; and the U.S. Patent Application Ser. No. 376,780 entitled "Sewing Machines Stitch Pattern Generation Form Stitch Data Stored in Static Memory", filed July 5, 1973 by John W. Wurst and issued Dec. 24, 1974 as U.S. Pat. No. 3,855,956 and assigned to The Singer Company.
Such an electrical signal generator, however, in order to obtain separately a first electrical signal associated with the first angular position of the main-shaft and a second electrical signal associated with the second angular position thereof, must be provided with two angular position detectors, i.e., a first angular position detector for detecting the first angular position of the main spindle and producing a first signal and a second angular position detector for detecting the second angular position of the main-shaft and producing a second signal, resulting in a complicated construction and high cost.
The object of the present invention is to obviate the above-mentioned disadvantages.